Exploring communication and collective behaviour between spatially organised inorganic protocell communities

A living system profoundly relies on mass, information and energy interactions through cell-cell and cell-environment networks. As a step towards understanding such interactions, it is beneficial to design and create bottom-up artificial living systems from non-living components, with a specific focus on synergistic interactivity between artificial cells (protocells) and their local environment. Although there are several routes for fabricating protocellular systems, we recognise key challenges associated with a) developing protocellular models with high levels of organisational tunability, b) achieving cell-environment bilateral communication, and c) realising autonomous self-assembly and regulation of protocell systems. The aim of this thesis is thus to review some matrix-based and matrix-free methods of inorganic protocell (colloidosome) 3D-spatial organisation, as judicious system designs capable of cell-cell and cell-environment communication, collective behaviours, and dynamic self-assembly, in close relation with local environments.The first experimental chapter details assembly of colloidosomes within hydrogel or coacervate-based matrices. A droplet microfluidic technique is employed as a novel method for encapsulating segregated colloidosome colonies within alginate hydrogel microspheres. The technique exploits high tunability for customisable size, ratio, microscale geometry, and 3D-patterning parameters. Benefiting from the versatility associated with such matrix-based systems, the second experimental chapter develops 3D-organised colloidosomes for collective signalling and emergent behaviours. Notably, spatially segregated colonies show proximity-mediated chemical communication with increased kinetics compared to analogous homogenous arrangements. This proximity-enhanced colloidosome signalling is exploited, alongside segregated ionic/covalent crosslinking transitions in the environment, to obtain simultaneous structural degradation and resilience of hydrogel hemispheres as a programmable mechanism for protocell ejection. Colloidosomes are also employed as simple signalling hotspots within coacervate-matrix systems. The final experimental chapter aims to re-imagine colloidosome organisation into a matrix-free system, capable of dynamic self-assembly and self-sorting via electrostatically-active membrane appendages. Alginate-coated and chitosan-coated colloidosomes are either co-assembled or self-sorted, in response to varied pH environments. Again, these systems are highly coordinated with their environment and as such, can be spatially pattered according to temporal pH changes through endogenous enzyme catalysis. Furthermore, a spatiotemporal effect on the rate of colloidosome communication in the presence of a hostile guest molecule is demonstrated. <br/

Nanobiotechnology: a solution to food insecurity, safety and sustainability

The problems of food insecurity, safety and sustainability occur mostly through the activities of pest and pathogens. The resistance of the causative agents on agricultural production coupled with potential health hazards posed on the environment by synthetic pesticides led to the search for an alternative to synthetic chemicals. Nanotechnology is currently the best candidate for ensuring food security, safety and water quality. National governments especially in developing countries are advised to mount regulating agencies that will be responsible for achieving food security and safety as already done in countries like USA, India and Indonesia among others. Considering the fact that we are now in a period when global population is steadily increasing and there is a very high demand for health food but high cost of production and need for sustainable agriculture has limited the profit margin made by farmers. The cause of naturally-occurring products with interesting antimicrobial eliciting properties and their derivatives has been getting more attention in recent years. Nanotechnology may have concrete solutions against many agriculture-related problems like insect pest management using traditional methods, adverse effects of chemical pesticides; development of improved crop varieties. As with any other technology, controversy surrounding nanotechnology is no exception in a heterogeneous society. Several concerns need to be addressed on different issues like food safety and beneficiaries of the technology.Keywords: Food-insecurity, pathogen, pest, safety, chemicals, materials, benefits, nanoparticles, biotechnolog

Microfluidic-Generated Biopolymer Microparticles as Cargo Delivery Systems

Droplet microfluidics offers precise and simultaneous control of multiple fluids at microscale, which enables synthesis of novel microparticles with compositional and structural diversity in a controllable way. The morphology and functionality of generated microparticles can be well designed by modulating the hydrodynamic profile as well as geometric structures. The synergistic combination of droplet microfluidics with biodegradable materials makes it possible to encapsulate actives/drugs inside microparticles at high efficiency for drug delivery. The utilization of these microfluidic-generated microparticles with the characteristics of easy biodegradability and good biocompatibility in the field of drug delivery has made considerable progress in recent years. In this review, the commonly used structures of microchannel and methods to generate microparticles with droplet microfluidics are introduced. In addition, recent advances of biodegradable microparticles in the application of drug delivery are discussed and summarized with the focus on two kinds of biopolymers for preparing biodegradable microspheres, natural biopolymers, and synthetic biopolymers. Next, environment-sensing microencapsulation systems have been discussed because of their ability to release drug upon external stimulation, thereby allowing on-demand drug delivery. Finally, current challenges of utilizing microparticles in drug delivery are pointed out and some perspectives for the future direction in research and applications are provided

CHITOSAN PARTICLES FOR THE CONTROLLED RELEASE OF PROTEINS

Back Ground Chitosan as a natural polymer has been fabulated into a number of formulations such as films, hydrogels and particles based on its excellent properties such as biodegradable, biocompotable, bioadhesive, permeartion-enhancement, antibiotic, antitumor etc. properties. Among them, chitosan microparticles found a lot of applications in pharmaceutics such as vaccine delivery, mucosal delivery and gene delivery, etc. Down to the nanoscale, chitosan nanoparticles have more attractive properties more than that of chitosan microparticles, which further widen the applications of chitosan particles in biomedicine and biopharmaceutics. Objective of this Thesis This thesis is aimed to prepare chitosan micro or nanoparticles to delivery proteins. What are the questions this thesis attempted to solve? 1) What are the proper preparation conditions of chitosan micro or nanoparticles? 2) How does the pH value affect the formation and protein encapsulation of chitosan nanoparticles? 3) How to overcome the burst release of chitosan nanoparticles? 4) How to overcome the aggregation disadvantage in the contritional preparation process of TPP-gelated chitosan microparticles? 5) How to construct a composite particles system to realize the sustainable release of proteins? What are the methods used in this thesis? 1) ionotropic gelation method to prepare chitosan nanoparticles 2) Emulsification-coacervation (NaOH) method to prepare chitosan microparticles 3) a polyelectrolytes coacervation method to prepare chitosan-BSA complexes 4) a microemulsion involved emulsification-coalescence method to prepare TPP-gelated chitosan microparticles 5) a nanoparticles encapsulation method to prepare composite particles. Results and Conclutions 1) the effect of preparation parameters on the properties of chitosan nanoparticles: 1a) the concentration of chitosan has no siganificant effect on particles yield, positively associated with particles size, size distribution, positively associated with BSA encapsulation efficiency in a specific concentration range; 1b) the mass matio of chitosan to TPP negatively associated with particles yield, positively associated with particle size and size distribution, negatively associated with BSA encapsulation efficiency; 1c) the concentration of BSA has no significant effect on particles yield, particle size or size distribution, negatively associated with BSA encapsulation efficiency in a specific concentration range. 2) a chitosan polymer chain conformation related mechanism is proposed through the study of the effect of pH value on the formation and BSA encapsulation of chitosan nanoparticles. 3) the most homogeneous and smooth chitosan particles could be obtained at the parameters of: 2% (m/v) chitosan solution, 2/10 w/o volume ratio, 4% Span 85 as susfactant, 5 Krpm homogenization speed and 3 times addition of NaOH solution as a coacervation agent. The obtained particles have a mean diameter of 9.4±1.9 m. The BSA loading test found that dispersed particles only could be obtained below the BSA concentration of 0.5% under above mentioned parameters. 4) a noval polyelectrolytes complex formed by TPP and BSA is obtained attempted to solve the burst release effect of chitosan nanoparticles. 5) a microemulsion involved emulsification-coalescence method is used to overcome the aggregation problem of TPP-gelated chitosan microparticles. 6) a chitosan nanoparticles encapsulated PLA composite particles are successfully constructed. What is new in this thesis? 1) to study the formation mechanism and protein encapsulation of chitosan nanoparticles through the study of the effect of pH value on their properties and propose the role of chitosan polymer chain conformation during this process, 2) a noval TPP-BSA polyelectrolytes complex is obtained base on the purpose to overcome the burst release effect of chitosan nanoparticles, 3) apply emulsification-coalescence method in which a microemulsion of cross-linking agent-TPP is used to solve the aggregation problem of TPP-gelated chitosan microparticles, 4) propose a chitosan nanoparticles encapsulated PLA composite particles to control the release of proteins. Where is the study of this thesis in the field? 1) Chitosan nanoparticles have been extensively investigated in the past few years and the factors which can affect the properties of chitosan nanoparticles have been well documented as well. This thesis provides the evidence from a new side to understand the formation and protein encapsulation mechanisms of chitosan nanoparticles. 2) New and highly effective methods have been proposed by others to prepare protein loaded chitosan microparticles such as sieving and microfluidic methods which can reproduceably scale up the production of monodispersed chitosan microparticles. This thesis just solved a technique problem in the conventional preparation process of TPP-gelated chitosan microparticles. 3) The proposed TPP-BSA polyelectrolytes complex could be an alternative route to overcome the burst release effect of chitosan nanoparticles. 4) The proposed chitosan nanoparticles encapsulated PLA composite particles is one of the solutions among other composite particles proposed by others

Sistemas microfuidicos de gotas para incorporaçao de acidos nucleicos em lipossomas cationicos e para transfecçao in vitro de células de mamiferos

Orientadores: Lucimara Gaziola de la Torre, Charles BaroudTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química, École Polytechnique - FrançaResumo: Este trabalho visou o uso de um sistema microfluídico de gotas para incorporar ácidos nucleicos em lipossomas catiônicos e outro para estudar o processo de transfecção em células de mamíferos. A primeira etapa do projeto utilizou um microdispositivo para incorporar pDNA em lipossomas catiônicos de modo a obter lipoplexos reprodutíveis e adequados para transfectar células dendríticas (DCs). Com esta finalidade, alguns parâmetros experimentais foram investigados, tais como vazões de entrada, manutenção das propriedades dos lipossomas após processamento no microdispositivo, características dos lipoplexos (tamanho, polidispersidade e carga) em função da razão molar de carga (R+/-) e do desenho do microdispositivo. Lipoplexos produzidos em microdispositivo com canal de serpentina largo e região de divisão de gotas que diminuem a polidispersidade dos lipoplexos, operando à razão de vazão água/óleo 0,25 e R+/- 1,5; 3; 5; 7 e 10 foram utilizados para transfectar DCs in vitro. Todos os lipoplexos foram capazes de transfectar as DCs e ao mesmo tempo proporciaonar a ativação das células. A segunda etapa do trabalho utilizou uma plataforma microfluídica de célula única para investigar e controlar as condições de transfecção, tendo em vista a otimização dos rendimentos de produção de proteínas recombinantes. Neste contexto, as células de ovário de hamster Chinês (CHO-S) foram transfectadas no microdispositivo com diferentes tipos de lipoplexos (R+/- 1,5; 3; 5) e monitoradas em relação à produção de proteína verde fluorescente (GFP) e viabilidade celular. A plataforma de célula única permite avaliar a heterogeneidade celular, revelando a presença de uma subpopulação que produz níveis elevados de GFP. Essas células com alta produção de GFP (HP) mostraram um aumento do tamanho celular em comparação à média da população. Além disso, a carga dos lipoplexes apresenta um importante papel na transfecção das células CHO-S, visto que os únicos lipoplexos com carga positiva R+/- 5 produziram mais HPs. A quantidade de pDNA entregue às células afeta a produção de proteína, já que os lipoplexos com mais pDNA R+/- 1,5 aumentaram a produtividade específica de GFP das HPs. Esta tese foi desenvolvida no âmbito de um programa de co-tutela entre a Universidade Estadual de Campinas, Brasil e a École Polytechnique, França. Em geral, este trabalho apresenta contribuições originais para as áreas da microfluídica e da entrega de genesAbstract: This work aimed at using one droplet-based microfluidic systems to incorporate nucleic acids into cationic liposomes and another one to study the mammalian cell transfection process. In the first part of this study we used a droplet-based microfluidic system to complex cationic liposomes with pDNA in order to obtain reproducible and suitable lipoplexes to dendritic cells (DCs) transfection. For this purpose, some experimental parameters were investigated, such as inlet flow rates, the maintenance of liposomes¿ properties after microfluidic processing, lipoplex characteristics (size, polydispersity and zeta potential) as function of molar charge ratio (R+/-) and microchip design. Lipoplexes produced in a microchip with large serpentine channel and split region, which decreases lipoplex polydispersity, operating at ratio aqueous/oil flow rate 0.25 and R+/- 1.5, 3, 5, 7 and 10 were used to transfect DCs in vitro. All lipoplexes transfected DCs and resulted in cell activation. In the second part of this study we used a single-cell microfluidic platform to investigate and control transfection conditions, in view of optimizing the recombinant protein production by transfected cells. Chinese hamster ovary cells (CHO-S) were transfected in microchip with different types of lipoplexes (R+/- 1.5, 3, 5) and monitored by green fluorescent protein (GFP) production and cell viability. The single-cell platform enables to assess the heterogeneities of CHO-S population, revealing the presence of a subpopulation producing significantly high levels of GFP. These high producers (HP) showed increased cell size in comparison to the average population. Moreover, the charge of lipoplexes shows an important role to transfect CHO-S, since the unique positive charged lipoplex R+/- 5 produced more HPs. Additionally, the amount of pDNA delivered affects protein production, since R+/- 1.5 with more pDNA increased GFP specific productivity of HPs. This thesis was developed under the joint graduate program of the University of Campinas, Brazil and École Polytechnique, France. In general, this work presents original contributions in the areas of microfluidics and gene deliveryDoutoradoDesenvolvimento de Processos BiotecnologicosDoutora em Engenharia Quimica2012/24797-2, 2014/10557-5FAPES

NANOEMULSIONS FOR PROSTRATE CANCER THERAPY: AN OVERVIEW

The objective of this review is to focus the inferences of low/poor bioavailability and lack of dose proportionality for the oral delivery of drugs in prostatecancer therapy. To overcome such problems, various formulation strategies has been reported including various methods for the use of surfactants,cyclodextrins, solid dispersions, micronization, permeation enhancers, and lipids. Flutamide is an antiandrogen drug and used for the therapy of prostate cancer. The flutamide drug is having limited clinical application due to its poor water solubility and needs enhancement of its dissolution rate in simulated gastric fluids. The lipid-based formulations such as nanoemulsion have been shown to improve the solubility and oral absorption of lipophilic drugs. To conclude, this article emphasizes the various approaches of nanoemulsion based formulation for prostate cancer therapy.Â

Functional Hydrophilic Polymers for Solution Assembly and Non-Viral Gene Therapy

This thesis examines functional hydrophilic polymers designed in linear and comb architectures and that carry functional moieties in the context of solution assembly and non-viral gene therapy. Specifically, polymers containing cations, zwitterions, and reactive groups are investigated as non-viral gene therapy reagents and at oil-water interfaces on droplets. Cations facilitate complexation of nucleic acids and interaction with cellular and nuclear membranes, while zwitterions impart stimuli-responsive solution properties and biocompatibility. Reactive groups, including alkenes, alkynes, and benzylic methylenes, permit post-polymerization modification leading to tunable polymer properties in solution and at interfaces. This work expands the knowledge base related to solution, interfacial, and DNA complexation properties imparted by the inclusion and arrangement of functional groups within hydrophilic polymers. Chapters 2-4 discuss polymers having a comb architecture designed for non-viral gene therapy. These polymers contain a polycyclooctene backbone and oligopeptide and zwitterionic pendent groups. Chapter 2 describes comb polymers with Simian Virus 40 nuclear localization sequence (SV40 NLS) pendent groups that interact with receptors on the nuclear membrane to provide enhanced nuclear uptake of complexed DNA. Cell culture experiments revealed a marked effect of oligopeptide orientation on the resulting gene expression levels provided by the NLS-containing comb polymers. Moreover, these polymers outperformed commercial transfection reagents, both in gene expression levels and cell viability. Chapter 3 describes the introduction of zwitterions into these comb polymers and investigates the impact of zwitterions on polymer-DNA complex (or ‘polyplex’) properties. Dispersing small amounts of zwitterion into comb polymers with SV40 NLS and oligolysine pendent groups improved gene expression levels. Chapter 4 describes the synthesis of comb polymers having oligoarginine sequences as pendent groups and properties of the corresponding polyplexes. Compared to oligolysine sequences, oligoarginine facilitated stronger polymer-DNA binding and allowed inclusion of higher loadings of biocompatible zwitterions without compromising the ability of the polymer to complex DNA. Chapters 5 and 6 investigate zwitterionic polymers at the oil-water interface of emulsion droplets. Experiments in Chapter 5 demonstrate the ability of zwitterionic sulfobetaine methacrylate polymers to stabilize oil-in-water droplets in pure water at room temperature, followed by coalescence upon increasing salt concentration or temperature. Integrating alkene and alkyne groups directly into the zwitterionic moiety allowed inclusion of high loadings of functional groups without interrupting the salt-triggered droplet coalescence exhibited by sulfobetaine homopolymers. Functional group placement was found to greatly impact interfacial properties. Chapter 6 describes the preparation of adhesive droplets from novel sulfur-based zwitterionic polymers. Droplet adhesion was modulated by the presence of salt and nucleophiles, and the resultant stability and adhesiveness of the droplets. The interdroplet interactions were found to dictate the mechanical properties of the emulsion and its stability upon application of centrifugal force

Microbubbling and microencapsulation by co-axial electrohydrodynamic atomization

Microbubbles coated with polymers or surfactants have been used in medical imaging for several years as ultrasound contrast agent particles and are now being investigated by researchers as drug and gene delivery vehicles and blood substitutes. Current methods available for the preparation of microbubbles are insufficient as they result in microbubbles with a wide size distribution and as such filtration is necessary before their use. With a view to fill the above demand, a detailed investigation has been carried out in this research to learn the viability of co-axial electrohydrodynamic atomization (CEHDA) technique to prepare microbubbles. The research also focuses on the effects of the process parameters such as flow rates, applied voltage and material parameters such as electrical conductivity, surface tension and viscosity with the objective of preparing polymer or surfactant coated stabilized microbubbles with diameters < 8 μm and with a narrow size distribution. A model glycerol-air system was used so that the CEHDA technique was modified to generate suspensions of microbubbles to a diameter < 8 μm with a narrow size distribution and then to characterise the CEHDA microbubbling process in terms of size and stability with varying process parameters and material parameters. Construction of a parametric plot between the air flow rate and the liquid flow rate was extremely useful in identifying the flow rate regime of air and liquid or suspension or solution for the continuous microbubbling of the system used. With further investigations into the CEHDA microbubbling technique, it was possible to develop strategies, first, to prepare suspensions of stabilized phospholipids-coated microbubbles with a mean diameter of ~ 5 μm and a polydispersivity index of 9%, and second, polymeric microspheres with a mean diameter of 400 nm and a polydispersivity index of 8% using a biocompatible polymer

Fabrication, Characterization and Biological Fate of Phytochemical Delivery System

Polymethoxyflvones (PMFs) are a group compounds with promising cancer preventing activities and many other health benefits. There\u27s a growing interest in fabricating delivery systems for PMFs as well as other phytochemicals due to their low water solubility. Firstly, we use nanoemulsion delivery system to encapsulate β-carotene. Sonication assisted method was developed to dissolve β-carotene to ensure minimum degradation. Powdered nanoemulsion was obtained after spray dry and freeze dry. Sample obtained after freeze dry showed better physiochemical characteristics. Then we use protein nanoparticle delivery system to encapsulate PMFS. The nanoparticle delivery system was fabricated by mixing the aqueous phase containing β-lactoglobulin with organic phase containing ethanol and tangeretin. Powder was obtained after vacuum evaporation of ethanol followed by freeze-drying. This powder can be easily dispersed into water and have similar property as freshly prepared, suggesting excellent applicability of the system as a convenient powder ingredient. Different delivery systems were made by mixing this powder with stock emulsion to represent various types of diets. These systems were then go through in vitro digestion process. The delivery system contained 4% oil exhibited the highest bioaccessibility of tangeretin due to increased amount of mixed micelle formed after digestion in simulated small intestine. The following permeability determination experiments on Caco-2 cell monolayer model suggested digested sample with higher oil content has higher permeability than PMF that did not go through the digestion process. In order to further study the uptake and internalization of PMFs, a new approach to visualize polymethoxyflavones (PMFs) inside the cell and in mice colon using a fluorescence microscope was developed. 5, 3\u27, 4\u27-tridemethylnobiletin (THN) was used for further study due to strong fluorescent intensity upon conjugation with DPBA. Fluorescence spectroscopy indicated this conjugate has the maximum excitation wavelength of 490 nm and maximum emission wavelength of 570 nm. Both mass spectroscopy and Raman spectroscopy confirmed the reaction between one or two hydroxyl group on THN and diphenyl boron group on DPBA. This method could easily detect the PMFs in the single suspend cell or in the attached cell. It can also be used to visualize PMFs absorbed by mouse tissue such as colon